This application is based on patent application No. 11-97993 filed in Japan, the contents of which are hereby incorporated by references.
1. Field of the Invention
The present invention relates to a method for handling waste oil which is to be taken out of a manufacturing line of (meth)acrylic acid and/or ester thereof. More specifically, the present invention relates to a method for stabilizing waste oil which is to be taken out of each chemical apparatus of the manufacturing line of (meth)acrylic acid and/or ester thereof.
2. Description of the Related Art
In a process of producing (meth)acrylic acid and/or ester thereof, stages such as distillation, extraction and crystallization are conducted for obtaining the (meth)acrylic acid and/or ester thereof by separating impurities from poor quality substance which is synthesized from raw material. In a stage of distillation, for example, waste oil (e.g. distillation residue) may be remained in a distillation apparatus (e.g. at the bottom of a distillation tower). The waste oil is drained through its bottom and treated as waste. In a process of producing acrylic acid for example, waste oil, which may be remained in a distillation apparatus (e.g. at the bottom of the distillation tower), contains undistilled acrylic acid in some amount, polymers of acrylic acid, and polymerization inhibitor accumulated after being used in the process of producing the acrylic acid. The waste oil is in the form similar to tar at an ordinary temperature. The waste oil is usually taken out of the distillation tower through its bottom, and is sent to a combustion apparatus where the waste oil is burned. Alternatively, the waste oil may be sent to a storage tank where the waste oil is stored for some time and sent through a pipeline to a combustion apparatus where the waste oil is burned. The waste oil may be viscous, and contains precipitates and polymerizable substances. The generated precipitates in the waste oil may attach to the inner surface of the distillation tower and/or of the pipeline, or the polymerizable substances in the waste oil may be polymerized in the distillation tower and in the pipeline which may cause clogging of the pipeline and affect the transportation of the waste oil thorough the pipeline and also adversely affect the drainage of the waste oil out of the distillation tower. The waste oil may be solidified in the storage tank which may arise difficulties in draining the waste oil out of the tank.
At this stage, no method has been suggested for solving the above-described problem, that is, a method for stabilizing the waste oil and handling it, such as draining it out of the distillation tower through its bottom, sending or transporting it through the pipeline, and storing it in the storage tank in a simple manner, while keeping the waste oil in a stable state.
Japanese Examined Patent Publication No. 60-43055 discloses a method for stabilizing a distillation residue liquid generated in the production of 2-hydroxyalkyl (meth)acrylate. This prior art method aims to prevent the distillation residue liquid from gelation which is taken place by ferric salt of organic carboxylic acid and complex salt of 2-hydroxylalkyl (meth)acrylate used as catalysts for addition reaction. For this purpose, at least one of water, acetic acid, salicylic acid, ethanol amines, and methanol is added to the distillation residue liquid. This method is effective in suppressing the gelation of the distillation residue liquid containing such catalysts. However, there is no description on the application of this method to the stabilization of waste oil (e.g. distillation residue oil) which is generated in the production of (meth)acrylic acid and its ester and contains no such catalysts.
An object of the present invention is to solve the above prior art problems and to provide a method for stabilizing waste oil without any problems.
As a result of studies, the present inventors have found a method for stabilizing waste oil which is to be drained from each chemical apparatus of a manufacturing line of (meth)acrylic acid and/or ester thereof.
The method which can solve above problems is to treat said waste oil which is to be taken out of each chemical apparatus of a manufacturing line of (meth)acrylic acid and/or ester thereof by coexisting with solvent.